Everyone is not familiar with the International Phonetic Alphabet (IPA). How can they pronounced words suggested in the answers? I think a "Listen" button to be add in the position of the answer where "teachers" suggested any word. It can be done adding a button in the "Markdown Editor" where "teachers" can add this feature in there answer proving IPA in a popup-ed box.
Even people who can read the IPA sometimes have trouble reproducing an utterance correctly! This of course is barring any transcription errors. That said, I'm definitely for the ability to attach audio to questions and answers. It would add a whole different dimension to possible questions: e.g., "I'm saying this like this, can you give me tips?". I don't think adding audio could be required though.
With HTML5 audio, it could be a really good experience, too. I worry about the file size and storage of clips though. I wonder what kind of changes to the software are possible.